The present invention concerns a baling press comprising two substantially parallel press plates and a force means for pressing these press plates against each other. In particular, the invention concerns fast and high-capacity baling presses to be used in baling cellulose.
Cellulose baling presses in present use are mainly based on one specific construction principle. The press comprises a horizontal, lower press plate which is stationary in relation to the base and an upper bracing plate fixedly attached thereto, above it, with the aid of posts or another joining structure. Between the bracing plates has been disposed a, likewise horizontal, movable press plate, which has been provided with a powerful hydraulic cylinder, braced against the bracing plate, for moving it in relation to the lower press plate and pressing it thereagainst, supported by guides or equivalent. Presses of this kind are intended in the first place for 200-kg bales, and the pressing force of the presses is on the order of 1000 tons.
In the press just described, concentration of the resistance to pressing constitutes a drawback. If the resistance to pressing, i.e., the bale which is being pressed is not constantly positioned in the center of the press, the centrally disposed hydraulic cylinder gives rise to an eccentric moment, which may cause breakage of the press. It should be noted that in practice the resistance to pressing may deviate from centered position even by several tens of centimetres; the consequence has in fact been instances in which the press was broken.
When the production rate in a cellulose mill exceeds 1000 tons per day, it becomes necessary to press one bale more frequently than every 20 seconds. This has necessitated dividing the production between two separate pressing and baling lines. The normal consumption of baling wire in a larger cellulose mill like this involves costs even in the neighbourhood of FIM 8000 per day, or FIM 3 million annually. To this must be added the costs for wire required in tying up large units when several bales are combined to make large units e.g. of 1600 kg each.
Furthermore, the 200-kg bales produced with existing baling presses are unsatisfactory because the baling wires running crosswise have to be manually removed in the paper mill. The bales are moreover of different sizes, and even otherwise defective, that is: there are internal gaps in the large-size unit, which cause soiling and a risk of bale disintgration and toppling.
Baling presses in present use are unable to press bales larger than those containing 200 kg. In endeavours to develop bigger and more efficient presses for larger bales and for increased pressing force, difficulties of structural designing have been encountered. However, press constructions of prior art are not applicable in higher capacity presses: the structure simply fails in lack of strength.
Developing higher capacity baling presses is desirable in order to eliminate the drawbacks that have been mentioned and also in order to reduce the transport costs. Cellulose transporting costs, e.g. on the order of FIM 160 to 280 per ton, are essentially directly proportional to the bale volume. Thus for instance increasing the efficiency of pressing by 10% would result in a corresponding reduction of transport costs.